Min and Max attributes now rely on type attribute for comparison

When used as HTML5 attributes, min and max were comparing as strings.  So an element of `<input min="10" data-bind="value:myNumber">` would validate successfully for a value of 5, because the string "5" is greater than the string "10".  This was understandably causing some problems.

This update changes the min and max validators so that they pay attention to the type attribute.  For example, the element `<input type="month" min="2010-03" data-bind="value:myMonth">` will use appropriate logic to ensure that the entered date is entered as a month and is March 2010 or later.  And an element of `<input type="number" min="10" data-bind="value:myNumber">` will fail validation if a value of 5 is entered.

Tests and Documentation updates included.